As a film deposition method of a semiconductor fabrication process, there is a known process which causes a first reaction gas to be adsorbed on a surface of a semiconductor wafer (hereinafter simply referred to as a “wafer”), which is used as a substrate, under a vacuum environment, and thereafter switches the gas that is supplied to a second reaction gas, in order to form one or a plurality of atomic or molecular layers using the reaction of the two gases. Such a deposition cycle is performed a plurality of times to stack and deposit the layers on the substrate. This known process is referred to as the Atomic Layer Deposition (ALD) or Molecular Layer Deposition (MLD). According to this known process, the film thickness can be controlled with a high accuracy depending on the number of cycles performed, and a satisfactory in-plane uniformity of the film quality can be achieved. Therefore, this known process is a promising technique that can cope with further reduced film thicknesses of semiconductor devices.
Such a film deposition method may be used to deposit a dielectric film having a high dielectric constant for use as a gate oxide film, for example. When silicon dioxide (SiO2) is deposited as the gate oxide film, a bis tertiary-butylamino Silane (BTBAS) gas or the like is used as a first reaction gas (or source gas) and an ozone gas or the like is used as a second gas (or oxidation gas).
As an apparatus for carrying out such a film deposition method, the use of a single-wafer deposition apparatus having a vacuum chamber and a shower head at a top center portion of the vacuum chamber has been under consideration. In such a film deposition apparatus, the reaction gases are introduced into the chamber from the top center portion, and unreacted gases and by-products are evacuated from a bottom portion of the chamber. When such a deposition chamber is used, it takes a long time for a purge gas to purge the reaction gases, resulting in an extremely long processing time because the number of cycles may reach several hundred. Therefore, a film deposition method and a film deposition apparatus that can achieve a high throughput are desired.
Under these circumstances, film deposition apparatuses having a vacuum chamber and a turntable that holds a plurality of wafers along a rotation direction have been considered to perform the ALD or MLD. More particularly, in such film deposition apparatuses, for example, a plurality of process areas are located at mutually separated positions in the rotation direction of the turntable within the vacuum chamber, and different reaction gases are supplied to the process areas to perform the film deposition process. In addition, a separating region is provided between the process areas in the rotation direction, and this separating region includes a separation gas supply means for supplying a separation gas which separates or isolates the atmospheres or environments of the process areas.
When performing the film deposition process, the separation gas is supplied from the separation gas supply means and spreads on both sides in the rotation direction of the turntable, to thereby form a separation space which avoids mixing of the reaction gases by the separating region. For example, the reaction gases supplied to the process areas are exhausted via an evacuation port that is provided within the vacuum chamber, together with the separation gas which spreads on both sides in the rotation direction. By supplying the process gases to the process areas and supplying the separation gas to the separating region, while rotating the turntable to alternately repeat a process of moving the wafers on the turntable from one process area to the other and vice versa, the ALD or MLD is performed. In such film deposition apparatuses, it is unnecessary to switch the gases in the processing atmosphere, and a high throughput can be expected because the film deposition can be made simultaneously on a plurality of wafers.
For example, Patent Document 1 proposes a film deposition apparatus with a vacuum chamber which has a flat cylinder shape and is divided into right and left areas. A separation gas outlet port is provided between the right semi-circular contour of the right area and the left semi-circular contour of the left area, that is, at a diametrical area of the vacuum chamber. In addition, Patent Document 2, for example, proposes a film deposition apparatus having a wafer support member (or turntable) which supports four wafers at equal distances along the rotation direction thereof, a first reaction gas ejection nozzle and a second reaction gas ejection nozzle which oppose the wafer support member and are arranged at equal distances along the rotation direction, and a separation gas nozzle is arranged between the first and second reaction gas nozzles. The film deposition process is performed by rotating the wafer support member horizontally. However, according to these proposed film deposition apparatuses, there is a problem in that the concentration of the reaction gas and the contact time with respect to the wafer are reduced in the process area as will be described later, to thereby reduce the film deposition rate with respect to the wafer; such a problem is not recognized, and a solution to this problem is not provided.
Furthermore, Patent Documents 3, 4, and 5 propose film deposition apparatuses that perform an atomic layer Chemical Vapor Deposition (CVD) to cause a plurality of gases to alternately be adsorbed on a target (corresponding to wafer), by rotating a susceptor which supports the wafer and supplying the source gas and the purge gas from above the susceptor. Patent Document 3 also proposes providing partition walls that extend in a radial direction from a center of the chamber, and gas ejection holes that are provided below the partition walls in order to supply the source gases or the purge gas to the susceptor, so that an inert gas is ejected from gas ejection holes to generate a gas curtain. However, even in this example, a problem of a reduced film deposition rate is not recognized, and thus cannot be solved.
Moreover, Patent Document 6 proposes an ALD apparatus that is provided with a turntable on the surface of which plural wafers are arranged along a rotation direction, and a chamber upper body that opposes the turntable. Plural suction zones (or supplying holes) that extend in radial directions of the turntable and supply different gases are provided on a lower surface of the chamber upper body and arranged with circumferential intervals. Between the adjacent supplying holes, there are provided two evacuation zones (or evacuation holes) that extend in the radius direction and arranged along a circumferential direction. In the lower surface of the chamber upper body, distances of the suction zones and the evacuation holes from the turntable are equal to each other, and a flat ceiling surface is formed. Reaction gases supplied from the suction zones during rotation of the turntable flow into a gap between the ceiling surface and the turntable and are evacuated from the evacuation zones adjacent to the suction zone that supplies the corresponding reaction gas. With this, the reaction gases are partitioned in corresponding areas where the corresponding gases are supplied, thereby carrying out the ALD process or the MLD process. However, the evacuation zones adjacent to each other are positioned close to each other, so that the reaction gases that proceed from the suction zone to the corresponding evacuation zone are inter-mixed with each other, and thus by-products that cause particles in the chamber may be produced.    Patent Document 1: U.S. Pat. No. 7,153,542.    Patent Document 2: Japanese Patent Application Laid-Open Publication No. 2001-254181.    Patent Document 3: Japanese Patent Application Laid-Open Publication No. 2007-247066.    Patent Document 4: United States Patent Application Publication No. 2007/0218701.    Patent Document 5: United States Patent Application Publication No. 2007/0218702.    Patent Document 6: Published Japanese translations of PCT international publication for Patent Application No. 2008-516428 (or United States Patent Application Publication No. 2006/0073276.)